U.S. Pat. Nos. 4,734,416 and 5,006,528 disclose aripiprazole, 7-{4-[4-(2,3-dichlorophenyl)-1-piperazinyl]butoxy}-3,4-dihydro-2(1H)-quinolinone or 7-{4-[4-(2,3-dichlorophenyl)-1-piperazinyl]butoxy}-3,4-dihydro carbostyril, as an atypical antipsychotic agent useful in the treatment of schizophrenia, bipolar disease, depression and other CNS disorders. Aripiprazole has the following chemical structure:

Aripiprazole is sold under the tradename Abilify®. It acts as a dopamine D2 partial agonist, serotonin 5-HT1A receptor agonist and is an antagonist of the serotonin 5-HT2A receptor. Abilify® is currently administered orally on a once-a-day dosing schedule as Abilify® (aripiprazole) Tablets, Abilify Discmelt® (aripiprazole) Orally Disintegrating Tablets and Abilify® (aripiprazole) Oral Solution. In one embodiment, Abilify® Injection for intramuscular use is a rapid-acting solution product for treating agitation associated with schizophrenia and bipolar disease. Poor and variable patient compliance with a once-a-day dosing schedule of psychiatric drugs has been reported.
Olanzapine (1,2-methyl-4-(4-methyl-1-piperazinyl)-10H-thieno[2,3-b][1,5]benzodiazepine) is a second generation antipsychotic drug marketed as Zyprexa®. It is useful for the treatment of disorders such as schizophrenia, bipolar disorder, psychotic depression, and Tourette syndrome. This active pharmaceutical ingredient acts as an antagonist on 5-HT2 serotonin receptors as well as the D1/D2 dopamine receptors, while also exhibiting anticholinergic and antimuscarinic properties. Olanzapine belongs to the benzodiazepine family, and has the following structure:

This compound is disclosed, for example, in U.S. Pat. Nos. 5,229,382 and 6,169,084. An extended release intramuscular injection product containing the water-insoluble salt olanzapine pamoate monohydrate is approved for use in schizophrenia.
Long-term stability is a critical consideration of drug formulation, expiry, shelf-life, and manufacturing. As such, stable pharmaceutical formulations that do not result in drug degradation of these and other antipsychotics through, e.g., hydrolysis and/or oxidation, are desired.